Engl Fireball Operating Manual page 3

8 Presence
This control shapes the Treble response in the power amp stage.
A TIP from the Designer:
To help you get acquainted with the amp's fundamental sounds, I recommend that you set all tone
controls to the center or 12 o'clock position. For ultra hi-gain sounds, your best bet is to turn the treble
and presence knobs well down to prevent the pickups and speakers from interacting at hi levels and
generating feedback (the recommended setting is somewhere in the 8 to 12 o'clock range). Since the
two knobs sweep through different frequency ranges and influence the signal at different places in the
amp's internal signal chain, you can dial in different combinations of treble and presence settings to
come up with many interesting sonic variations.
9 Ultra Gain
This button sets the preamp to Ultra Gain mode, which makes the amp's input stage extremely sensitive.
In this operating mode, the preamp is saturated at very low signal levels, which elicits a heavy lead sound
suitable for soloing or playing power chords.
You can also activate this function via a footswitch connected to jack 18. When a footswitch is plugged
in, the front panel Ultra Gain button is disabled. The red LED lights up to indicate Ultra Gain is active.
10 Master A - (Normal Gain)
Located after the effects loop in the signal chain, this knob determines the overall volume of the power
amp when Normal Gain preamp mode is selected. Note that this is a dedicated knob with a fixed
assignment to Normal Gain mode. However, when you connect a footswitch to jack 18, the knob is no
longer assigned exclusively to Normal Gain mode. This means that you can select the master A or the
master B volume knob via footswitch to activate two different master volumes for each mode. To learn
more about selecting modes and master levels, see section 18.
The red LED next to the knob lights up when this knob determines the master volume level.
11 Master B - (Ultra Gain)
Located after the effects loop in the signal chain, this knob determines the overall volume of the power
amp when Ultra Gain preamp mode is selected. Note that this is a dedicated knob with a fixed
assignment to Ultra Gain mode. However, when you connect a footswitch to jack 18, the knob is no
longer assigned exclusively to Ultra Gain mode. This means that you can select the master B or the
master A volume knob via footswitch to activate two different master volumes for each mode. To learn
more about selecting modes and master levels, see section 18.
The green LED next to the knob lights up when this knob determines the master volume level.
TIP from the Designer:
This option of using a footswitch to select the two master A and B knobs gives you another interesting
switching alternative: You can dial in two different volume levels and activate them in combination with
the amp's two operating modes. That gives you four basic sonic variations, each of which supports
different playing techniques: In effect, you get footswitchable clean (or slightly dirty) rhythm and lead
tones in normal mode, and overdriven preamp tones in Ultra Gain mode for power chords or distorted
lead guitar. And by working your guitar's volume knob, you can expand this palette of tones
accordingly.
12 POWER TUBE MONITOR V1
This LED lights up when the current sent through the V1 power amp tube was too high and the power
tube monitor system has switched that tube off.
13 POWER TUBE MONITOR V2
This LED lights up when the current sent through the V2 power amp tube was too high and the power
tube monitor system has switched that tube off.
A few words on the POWER TUBE MONITOR system:
The electronic power amp monitoring system constantly gauges the current sent to the two power amp
tubes. If it rises to too high a level, the system shuts down the given tube.
This can occur when the amp is operated incorrectly (for example, if the impedance is wrong due to an
incorrect speaker load), at extreme power spikes, or when a tube is defective.
Reset this electronic monitoring system by switching the standby switch on and off again. When you
press the standby switch to turn the amp on again, the system again measures the current sent to the
tube. If it is still too high, the power amp must be checked by a service technician, and the tube may
have to be replaced if it is defective.
14 Stand By
Power amp standby switch: Use this switch to silence (0 position) the amp when you take a lengthier
break. The amp's tubes stay warm, which means that it is ready to roll immediately when you switch it
back to full power. Note that for reasons of tube monitoring, the amp still receives a very low signal
level when standby is activated.
To reset the power tube monitoring circuitry, press the standby switch briefly (see Power Tube Monitor).
15 Power
AC power on/off.